In the living body, especially in mitochondria, microsomes, leucocytes and the like, a lot of reactive oxygen species (radicals) having high reactivity, such as O2− (superoxide anion radical), H2O2 (hydrogen peroxide), HO. (hydroxyl radical) and 1O2 (singlet oxygen) as an excited molecular species, are generated. It is believed that they are involved in biological regulation including immunological self-defense, biochemical reactions and the like. Nitric oxide (NO) is an unstable short-lived radical species. It has been revealed that this substance also has important functions in a living body as one of the reactive oxygen species (Gendai Kagaku (Chemistry Today), April, 1994, feature article).
In normal cells, the amount of the generation of these reactive oxygen species is approximately 1% of the equivalent amount of the major oxidation-reduction reactions, and they are successively metabolized by catabolic enzymes and the like. The 95% or more of oxygen inhaled by a human by respiration is reduced to water via usual metabolic processes. However, the residue, i.e., some percents of the inhaled oxygen, is left behind as reactive oxygen species oozing from the electron transport systems in mitochondria or microsomes. Most of the reactive oxygen species are eliminated by enzymes for antioxidation such as superoxide dismutase, catalase, and glutathione peroxidase and the like.
However, the reactive oxygen species generated are not completely eliminated by these antioxidation enzymes, and some remained reactive oxygen species result in the oxidation of proteins, lipids, nucleic acids and the like. Although a part of the oxidized substances are restored by other biophylactic mechanisms, substances irreversibly damaged by oxidation are gradually generated. As a result, they are believed to lead to diseases and senescence.
Furthermore, it is well known that expression amounts of antioxidation enzymes such as superoxide dismutase decrease with aging. When the metabolic ability against these oxidized substances becomes insufficient, resulting in accumulation thereof, because of reduced metabolic ability against reactive oxygen species due to senescence as well as because of excessive productions of reactive oxygen species by pathologic conditions, non-specifically oxidized cellular components such as lipids eventually trigger cell death due to the disorders. This phenomenon is one of causes of senescence and various diseases such as Alzheimer's disease.
Examples of diseases in which reactive oxygen species is involved include cancer, diabetes mellitus, atopic dermatitis, Alzheimer's disease, retinitis pigmentosa and the like, and it is considered that excessive state of reactive oxygen species is involved in 90% of human diseases in their certain progression stages. The 90% or more of inhaled oxygen is metabolized in mitochondria, which is the main organelle to generate the reactive oxygen species in a cell. When the balance between the reactive oxygen species generated in mitochondria and the ability of antioxidation system cannot be maintained due to a hereditary disease or aging, the residue of the reactive oxygen species uneliminated will leak from mitochondria to damage the cell, which may induce senescence and cell death due to apoptosis.
As a means for quenching the reactive oxygen species, electrolyzed water with the oxidation reduction potential of −200 to −250 mV at the maximum has been developed as reduced water, and water alkalized by electrolysis to pH 9 to 11 has also been developed (for example, Tanigoshi, K., “Kyo kara Monoshiri Series—Tokoton Yasashii Mizu no Hon (Series of well-informed person from today—Entirely easy book about water)”, First edition, Nikkan Kogyo Shimbun, November, 2001, pp. 100-124). Furthermore, it is known that highly active metal fineparticles, e.g., platinum colloid, decompose H2O2 (hydrogen peroxide), which is one of the reactive oxygen species (for example, Japanese Patent Unexamined Publication (KOKAI) No. 10-68008, paragraph 0040). However, there is no literature reporting that platinum colloid has the quenching ability of superoxide radical or nitric oxide in vivo.
As for methods of production of highly active metal fineparticles, various methods have been known for a long time (for example, Japanese Patent Publication (KOKOKU) Nos. 57-43125, 59-120249, Japanese Patent Unexamined Publication No. 9-225317 and the like).